Experiment 2 - biochemical changes on postharvest in fruits and vegetables Flashcards
major componsent in most fruits and vegetables
water
major factor affecting quality of fruits and vegetables
water loss or transpiration
Effects of water loss to fruits and vegetables
wilting
shriveling
flacidness
soft texture
loss of nutritional value
predominant energy sources for cells
carbohydrates
carbohydrates representes what when an edible plant tissue is removed from the parent plant
carbohydrates represent tbe reserves necessary to maintain cellular function
primary cell wall
a thin, flexible, and extensible layer formed while the cell is growing
secondary cell wall
forms as a thick layer inside the primary cell wall after the cell is fully grown
middle lamella
forms at the interface between adjacent plant cells; promotes cell-to-cell adhesion
cellulose
linear polymer of beta-1,4-linked beta glucose residues deposited in the wall to form microfibrils
hemicellulose
branched and are mainly composed of several neutral sugars like xylose
pectins
linear or branched polymers that are rich in galacturonic acid and dispersed throughout the primary cell wall
Happens due to the loosening of the hemicellulose-cellulose network, solubilization and depolymerization of pectin and loss of pectic side chains
cell-wall swelling
formula for percent calcium pectate
%CP = (g of precipitate/g of sample in aliqout)*100%
what are the three types of carbohydrates
structural
soluble
storage
carbohydrates used in metabolic processes such as glycolysis and secondary metabolic pathways
soluble carbohydrates
examples of soluble carbohydrates
glucose
fructose
sucrose
an insoluble homoglucan composed of two polymers of glucose, amylopectin and amylose
starch
amylopectin
branched molecule linked by alpha-1,4-glycosidic bonds with occasional alpha-1,6-glycosidic bonds
amylose
linear polysaccharide joined by the alpha-1,4-glycosidic linkages
most common organic acids in edible plant
mono-, di-, and tri-carboxylic acids
typically associated with less mature fruits
organic acid accumulation
responsible for the aroma of many fruits
esters
plant secondary metabolites that affect the appearance (color), taste, and flavor of edible plant tissues
phenolic compounds
enzymatic oxidation of phenolic compounds occurs by the action of
polyphenol oxidase (ppo)
regulate metabolism via their enzymatic functions
proteins and amimo acid
play a major role in the storage of nitrogen for growth in plants
free amino acids and their water-soluble derivatives
4 general types of lipids in plants
triacyglycerides
phospholipids
waxes
isoprene-derived lipids
these occurs if antioxidative defense systems are compramised
lipid peroxidation and membrane deterioration
plant volatole organic compounds
are secondary metabolites that play an important role in biotic interactions and abiotic stress responses
plant hormones
chemical compounds that potentiate a signaling network and regulate the metabolic systems
examples of plant growth regulators
ethylene
auxins
gibberellins
abscisic acid
cytokinins
ethylene is produced from
methionine
phenotypic changes in response fk ethylene are determined by
- perception of hormone
- transduction of signal through gene expression regulators
- expression of gene and synthesis of proteins sensitive to the received ethylene signal
compositioms of fruits
water
carbohydrates
organic acids
phenolics
proteins and amino acids
lipids
pigments
volatile organic compounds
hormones